Deep brain stimulation in the treatment of severe dystonia

A retrospective study of a consecutive series of 19 patients with medically intractable dystonia treated with uni- or bilateral deep brain stimulation (DBS) is reported. A minimal follow-up of 6 months was available, up to el even years in one patient. The first twelve consecutive patients (4 with pr imary and 8 with secondary dystonia) were treated with chronic stimulation of the posterior part of the ventrolateral thalamic nucleus (VLp). In this group global functional outcome was improved in 8 patients, although dyston ia movement and disability scale scores did not show significant improvemen t. Of the 12 patients treated first by VLp DBS, three (1 primary and 2 seco ndary dystonia) underwent pallidal (GPi) DBS after the VLp DBS failed to im prove their symptoms. The last seven consecutive patients (5 primary and 2 secondary dystonia) were treated directly with GPi DBS. Extracranial infect ion prevented chronic GPi DBS in one patient. In another GPi patient, preli minary negative tests with the electrodes discouraged implantation of the s timulators, and the patient was not treated with chronic DBS. In the remain ing group of eight patients including those previously treated with VLp DBS , chronic GPi DBS resulted in a significant improvement in the dystonia mov ement scale and disability scores. Although this is a retrospective study d ealing with dystonia of heterogeneous etiology, the results strongly sugges t that GPi DBS has a better outcome than VLp DBS.